1. Field of the Invention
The present invention relates to a sheet handling machine used for, for example an automated teller machine (ATM), and more particularly, it relates to a sheet handling machine suitable for the handling of various bills different in size and thickness all over the world.
2. Description of the Related Art
An ATM is generally constructed in such a manner that bills to be deposited are directly inserted into the deposit port of the ATM, the inserted bills are automatically checked and counted by the bill handling machine of the ATM, the results thereof are displayed in real time, an approval (validation) of the display is entered by a user, and then deposit work for each handling is finished. Such a bill handling machine was constructed and adjusted specifically for bills of each country, because it was only necessary to handle the bills of Japan, Korea or the like, in which it was installed. Especially, sheet thickness checking means for checking the overlapped conveying of bills or the presence of foreign objects on a sheet surface needed to check only the thickness of one kind, as the thickness of a bill distributed in each country, Japan, Korea or the like, is constant irrespective of the kind of a bill.
As such conventional sheet thickness checking means for checking the thickness of one kind, there is, for example “OVERLAPPED SHEET FEEDING DETECTOR” disclosed in JP-A-5-278901. The overlapped sheet feeding detector disclosed therein comprises: a reference roller as a reference for thickness measurement; a detecting roller brought into contact with the reference roller to be displaced; converting means for converting the displacement of the detecting roller into an electric signal; correcting means for correcting an error intrinsic to the reference roller based on the integrated value of the outputs of the converting means. Thus, detecting accuracy is prevented from being affected by the machining accuracy of the reference roller.